Usage of compliant rollers in electrophotographic apparatus is well known, which compliant rollers may incorporate a removable sleeve member mounted concentrically around a mandrel. Single-sleeved and double-sleeved compliant rollers have been disclosed, e.g., sleeved imaging rollers, sleeved intermediate transfer rollers, and sleeved rollers for use in a fusing station. Thus in an electrostatographic machine employing a sleeved roller, a toner image is typically formed on an imaging member, transferred in a first transfer operation from the imaging member to an intermediate transfer member, and subsequently transferred in a second transfer operation from the intermediate transfer member to a receiver member (e.g., paper), whereupon the toner image on the receiver is fixed thereon in a fusing station.
Compliant intermediate transfer rollers have for example been disclosed in the Rimai, et al. patent (U.S. Pat. No. 5,084,735), the Zaretsky and Gomes patent (U.S. Pat. No. 5,370,961), the Zaretsky patent (U.S. Pat. No. 5,187,526) and the Bucks, et al. patent (U.S. Pat. No. 5,701,567). In these exemplary patents a compliant intermediate transfer roller includes a central member to which is adhered a coating of a thick compliant layer having a relatively thin hard overcoat, which roller improves the quality of electrostatic toner transfer from an imaging member to a receiver as compared to a non-compliant intermediate roller.
The use of a removable endless belt or tubular type of blanket on an intermediate roller has long been practiced in the offset lithographic printing industry. As disclosed, for example, in the Julian patent (U.S. Pat. No. 4,144,812) an intermediate lithographic roller comprises a portion having a slightly smaller diameter than the main body of the roller, such that a blanket member may be slid along this narrower portion until it reaches a location where a set of holes located in the roller allow a fluid under pressure, e.g., pressurized air, to pass through the holes, thereby stretching the blanket member and allowing the entire blanket member to be slid onto the main body of the roller. After the blanket is located in a suitable position, the source of pressurized air or fluid under pressure is turned off, thereby allowing the blanket member to relax to a condition of smaller strain, such strain being sufficient to cause the blanket member to snugly embrace the roller. The Gelinas patent (U.S. Pat. No. 5,894,796) discloses that the tubular blanket may be made of materials including rubbers and plastics and may be reinforced by an inner layer of aluminum or other metal.
An intermediate transfer roller having a rigid core and a removable, replaceable intermediate transfer blanket has been disclosed in Landa, et al. (U.S. Pat. No. 5,335,054), and in Gazit, et al. (U.S. Pat. No. 5,745,829), whereby the intermediate transfer blanket is fixedly and replaceably secured and attached to the core. The intermediate transfer blanket includes a substantially rectangular sheet mechanically held to the core by grippers. The core (or drum) has recesses where the grippers are located. It is disadvantageous that the entire circumference of the intermediate transfer drum cannot be utilized for transfer because the blanket does not form a continuous covering of the core surface. Moreover, particulate contamination tends to collect in the unavoidable gap between the ends of the blanket.
An electrostatographic imaging member in the form of a removable replaceable endless imaging belt on a rigid roller is disclosed in Yu, et al. (U.S. Pat. No. 5,415,961). The electrostatographic imaging member is placed on the rigid roller and removed from the rigid roller by stretching the endless imaging belt with a pressurized fluid.
The Mammino, et al. patents (U.S. Pat. Nos. 5,298,956 and 5,409,557) disclose a reinforced seamless intermediate transfer member that may be in the shape of a belt, sleeve, tube or roll and including a reinforcing member in an endless configuration having filler material and electrical property regulating material on, around or embedded in the reinforcing member.
The May and Tombs patents (U.S. Pat. Nos. 5,715,505 and 5,828,931) disclose a primary image-forming roller including a thick compliant blanket layer adherently coated on a core member, the thick compliant blanket surrounded by a relatively thin photoconductive structure. The compliant primary imaging roller provides improved electrostatic transfer of a toner image directly to a receiver member. It is further disclosed that the compliant imaging roller can be used bifunctionally, i.e., it may serve as an intermediate member for electrostatic transfer of a toner image to a receiver. The May and Tombs patent (U.S. Pat. No. 5,732,311) discloses a compliant electrographic primary image-forming roller.
The Chowdry, et al. patent (U.S. Pat. No. 6,605,399) discloses a sleeved compliant primary image-forming roller and a method of making such a roller. The sleeve is a photoconductive member, the sleeve resting on a compliant layer coated on a core member. This has certain advantages over U.S. Pat. No. 5,715,505 and U.S. Pat. No. 5,828,931, in that the coatings on the roller are made more reliably and more cheaply, and also in that the photoconductive sleeve may be readily removed and replaced when at the end of its useful life, thereby lowering cost and reducing downtime. The Chowdry, et al. patent (U.S. Pat. No. 6,605,399) also includes an advantage over U.S. Pat. No. 5,415,961 by providing a core member coated by a thick compliant layer over which the sleeve member is placeable and removable. However, in certain embodiments of this Chowdry, et al. patent, the rigid core member is electrically biased to effect transfer of toner, and because the electrical properties of the compliant layer coated on the core member alter with age, the compliant layer has a finite lifetime requiring expensive periodic replacement of the coated core member. Moreover, the compliant layer is disadvantageously subject to damage when removing or replacing a sleeve member, and such damage may necessitate recoating or replacing the costly core member.
The Shifley, et al. patents (U.S. Pat. Nos. 6,259,873, 6,263,177 and U.S. Pat. No. 6,484,002) disclose apparatus including a roller (such as a photoconductive roller or an intermediate transfer roller) which roller has a removable replaceable surface or sleeve, and which roller is supported at one end in cantilevered fashion during sleeve removal or replacement via the other end of the roller. For operation of the roller, the roller is supported at both ends. A disconnectable supportive member is provided that can be disengaged and moved away from the roller so as to provide a free end for purpose of sleeve removal or replacement. This supportive member is moved back so as to engage and support the roller for operation.
The Cormier, et al. patent (U.S. Pat. No. 6,394,943) describes an image transfer drum inclusive of a mandrel having an air bearing to facilitate loading and removal of a resilient sleeve. The air bearing is provided with a pair of cooperating plates one of which is scored with equally spaced and radially extending grooves. When urged together, the plates define a central air chamber and a plurality of radially-extending passages serving to direct pressurized air radially from one end of the mandrel, at which end the sleeve can be removed and replaced. The pressurized air is conveyed to the central chamber via a pipe passing into the mandrel at the other end of the mandrel, at which other end the mandrel is supported in cantilever fashion during removal or replacement of a sleeve.
Advantage over the Chowdry, et al. patent (U.S. Pat. No. 6,605,399) and the Cormier, et al. patent (U.S. Pat. No. 6,394,943) is obtained by providing an electrostatographic double-sleeved roller, as disclosed in the Chowdry, et al. patent (U.S. Pat. No. 6,377,772). Such a type of double-sleeved roller (DSR) can be useful for a number of applications in an electrostatographic machine, for example as a primary image-forming member or as an intermediate transfer member. The DSR includes a cylindrical rigid core member, a replaceable removable multilayer inner sleeve member (ISM) in the shape of an endless tubular belt including at least one compliant layer (e.g., made of a polyurethane) such that the ISM surrounds and nonadhesively intimately contacts the core member, and a replaceable removable multilayer outer sleeve member (OSM) in the shape of an endless tubular belt including at least one synthetic layer such that the OSM surrounds and nonadhesively intimately contacts the ISM. The synthetic layer may include, for example, a plastic, a polymer, a copolymer, an elastomer, a foam, a photoconductive material, a material including filler particles, a material comprising two or more phases, or a material reinforced with fibers. Because of the double-sleeve construction, an accurately dimensioned core member can have a long life without need of replacement. Moreover, the core member can advantageously remain fixed to the electrostatographic apparatus in which it is mounted when a sleeve member is replaced, and in a preferred embodiment either or both OSM and ISM are removable from the same end of the roller. A DSR, as disclosed in the Chowdry, et al. patent (U.S. Pat. No. 6,377,772), has an extra advantage in that a stiffening layer can be included as an exterior outer surface of an ISM or more preferably as an exterior inner surface of an OSM, thereby avoiding certain coating complications, and facilitating mounting and demounting of the sleeves. Additionally, overall operating costs are reduced, inasmuch as either sleeve may be replaced without replacing the other, or else the inner and outer sleeves may be replaced with differing frequencies. Thus an inner or outer sleeve member can easily and independently be replaced on account of wear or damage, or replaced when at the end of a predetermined operational life. An expensive, finely toleranced core member can thereby be retained for long operational usage with many generations of sleeve members.
The Aslam, et al. patents (U.S. Pat. Nos. 6,393,249 and U.S. Pat. No. 6,567,641) disclose double-sleeved rollers for use in a fusing station of an electrostatographic machine, e.g., as fuser rollers, as pressure rollers, or both.
An inner sleeve member (ISM) employed according to the Chowdry, et al. patent (U.S. Pat. No. 6,377,772) includes a flexible high-modulus tubular band, e.g., as a strengthening band or backing layer concentric with and supporting an adhered compliant layer. With the outer sleeve member (OSM) removed, this backing layer facilitates handling of the ISM during its removal or replacement using a pressurized air technique akin to that disclosed in the Julian patent (U.S. Pat. No. 4,144,812). However, to manufacture such a reinforced ISM generally requires a costly coating process. Thus there is a need to reduce manufacturing expense. One solution is to utilize a relatively cheap, non-reinforced, compliant ISM, i.e., an ISM having no high-modulus band or backing layer, such as is disclosed below for inclusion in the present invention. However, a non-reinforced relatively stretchable ISM (not contemplated in the Chowdry, et al. patent (U.S. Pat. No. 6,377,772)) has a propensity to exhibit edge disturbance when the pressurized air technique is used to expand and axially slide the OSM over the ISM (prior to removing the ISM). There is, therefore, a companion need for a specialized mandrel to securely support a non-reinforced ISM during mounting and demounting of an OSM of a double-sleeved roller. Moreover, there is an ancillary need for such a mandrel to provide, at a lower cost than in the prior art, delivery of pressurized air for use with both the ISM and the OSM. To satisfy these needs, the present invention provides a novel double-sleeved roller which includes such a mandrel and such a non-reinforced ISM.